Here is the full list of all 26 SUPERHOT achievements. It takes around 20-25 hours to unlock all of the achievements on Windows.
Kill 3 Red Dudes with one rifle burst.
Kill an enemy by jumping on him.
Kill 100 Red Dudes with a katana.
Cut bullet with a katana.
Kill 100 Red Dudes with a rifle.
Kill 2 Red Dudes with one katana throw.
Kill 100 Red Dudes with a shotgun.
Kill 100 Red Dudes using melee.
Score 100 headshots.
Complete the game.
Get back to the system after being expelled.
Kill 100 Red Dudes with a pistol.
Complete SERV level.
Complete SUBWAY level.
Upload a replay on killstagram.com
Shoot down a bullet with a bullet.
Kill over 1987 Red Dudes in endless mode.
Kill 3 Red Dudes with one shotgun shot.
Unlock all endless levels.
Become part of the community.
Find all secrets.
Launch every app in the system.
Beat all Challenges.
Get RED ending in every level of SPEEDRUN challenge.
Get RED ending in every level of SPEEDRUNrt challenge.